In an electrophotographic type image forming apparatus, a latent image formed on a surface of a photosensitive drum or the like is developed into a toner image by a development device. To the development device, a toner is supplied from a toner container such as a toner case or an intermediate hopper.
The toner container has a replenishment port through which the toner is supplied to the development device. The replenishment port is opened and closed by a shutter mechanism. An example of the shutter mechanism will be described with reference to FIG. 11A and FIG. 11B. In the shutter mechanism, a replenishment port 102 is formed in a duct 101 of a container main body, and a cylindrical shaped shutter member 104 is rotatably supported in the duct 101. On an outer circumferential wall of the shutter member 104, a discharge port 105 through which the toner is discharged is formed. Around the discharge port 105, a seal member 106 is provided. The shutter member 104 is rotated between an opening position (refer to FIG. 11A) where the discharge port 105 is communicated with the replenishment port 102 to allow the toner to be discharged from the container main body and a closing position (refer to FIG. 11B) where the discharge port 105 is retracted from the replenishment port 102 to restrict the replenishment of the toner to open and close the replenishment port 102.
In such a shutter mechanism, when the shutter member 104 is rotated in the counterclockwise direction (refer to an arrow in FIG. 11A) from the opening position to the closing position, the toner is scraped in the counterclockwise direction by side faces of the discharge port 105 and the seal member 106. Although almost of the scraped toner is fallen through the discharge port 105 into the replenishment port 102, a part of the scraped toner tends to adhere on an edge portion 102a of a downstream side face of the replenishment port 102 in a direction in which the shutter member 104 is rotated from the opening position to the closing position. As shown in FIG. 11B, if the adhered toner T is accumulated on the edge portion 102a, the adhered toner may be scattered or fallen around the replenishment port 102 and then contaminate the circumference.
Regarding the toner contamination, the Patent Document 1 discloses a toner container including a seal member arranged inside the replenishment port 102 of the duct 101. In addition, the Patent Document 2 discloses a toner container including a cover member rotatably provided outside a shutter mechanism. The cover member is configured to cover a circumference of the replenishment port to prevent the toner scattering.